The invention relates to engines, and more particularly, to engines having centrifugal oil separators.
One disadvantage of using four-stroke internal combustion engines for outdoor power tools traditionally has been the inability to operate the engine upside down or at extreme angles that may be required by the operator. Oil in the crankcase in those instances would tend to drain through the engine block and into either the air/fuel induction system, the combustion chamber, or the carburetor, thereby upsetting otherwise efficient fuel combustion during operation.
The present invention is directed to an engine comprising a crankcase, a cylinder communicating with the crankcase, and a piston coupled for reciprocation in the cylinder. The piston reciprocates between a first position and a second position that is farther from the crankcase than the first position. Movement of the piston from the first position to the second position decreases a crankcase pressure and movement of the piston from the second position to the first position increases the crankcase pressure. The engine also includes a ventilator system and a rotating shaft within the crankcase. The ventilator system includes a stationary aperture in the crankcase and a separator rotatable with the shaft. The separator includes a first side, an opposite second side, and an outer edge between the first and second sides. The first side faces a crankcase wall and includes an annular groove in fluid flow communication with the aperture during rotation of the shaft. The separator also includes at least one radial passageway extending between the annular groove and the outer edge.
Another embodiment of the present invention is directed to a breather and separator assembly for an engine. The engine includes a crankcase, a cylinder communicating with the crankcase, and a piston coupled for reciprocation in the cylinder. The piston reciprocates between the first position and the second position that is farther from the crankcase than the first position. The engine includes a rotating shaft and a crankcase wall that includes a stationary aperture fluidly connected to an air/fuel induction system. The breather and separator assembly is separate from the shaft and adapted to be rotatable with the shaft. The breather and separator assembly includes a first side, an opposite second side, and an outer edge between the first and second sides. The first side is adapted to face the crankcase wall and has an annular groove adapted to be in fluid flow communication with the aperture during rotation of the rotating shaft. The breather and separator assembly also includes at least one radial passageway extending between the annular groove and the outer edge.